Catalyst deactivation is a common, well known problem in industries, such as the petrochemical industry. It is a complex phenomenon, involving the coating of catalysts with a deposit, leading to partial or complete deactivation. The most widely known form of this phenomenon is deactivation via coke formation.
To say coke formation is a complex process is an understatement. Different variables, including the catalyst itself, the feedstock, and the process in which the catalyst is involved, are all material to its formation. To generalize, coke formation results from carbonaceous residues covering active sites of a heterogeneous catalyst surface, leading to reduction of catalytic activity.
This reduction in catalyst activity is a problem of great and growing concern in industrial catalytic processes and leads to increased costs per annum in the billions, due to the need to replace catalysts, and process shutdowns resulting from this need.
The standard way to reactivate a deactivated catalyst is to burn deposited coke off of a catalyst surface. The resulting, reactivated catalyst never has activity equal to its activity at the start. Indeed, there is a loss of activity after every regeneration cycle, until it is not practical to regenerate the spent catalyst.
Different processes use different catalysts. Hydrocracking catalysts, in general, comprise a zeolite, a binder material, and one or more active metals. Such catalysts are the focus of this invention. All of these catalysts comprise a zeolite, a binder, and one or more catalytically active metals.
The invention described herein is directed to using regenerated spent catalyst as the binder, combined with a fresh or fresher hydrocracking or hydrotreating catalyst, so as to minimize economic loss. In brief, spent catalyst is prepared so that it can be used as a binder, and then combined with fresh or fresher hydrotreating and/or hydrocracking catalyst, optionally with additional catalytically active metal. While not wishing to be bound to any particular theory or mechanism, it is believed that hydroxyl groups on regenerated, spent catalyst condense to form covalent bonds between heteroatoms, connected via an oxygen bridge.
The prior art shows the long standing interest in this area of technology. RO 109713, which is considered the most relevant prior art, teaches washing spent catalyst with HNO3, to generate hydroxyl groups. The resulting, washed spent catalyst is then used with a new catalyst. HNO3 is known to attack alumina, but not silica. Ni and Cr are the only active metals described, and Cr is not a metal which is known in hydrocracking catalysts.
U.S. Pat. No. 5,061,362, to Yamamoto, et al., combine two, independent catalysts in oil (a direct desulfurization catalyst, and a Mo free, spent FCC catalyst).
U.S. Pat. No. 4,410,443 discusses technology which is also seen in, e.g., U.S. Pat. No. 3,538,017 and EP 568407, all of which deal with recovery of active metal from spent catalysts, and reusing the metal.
U.S. Pat. No. 3,932,269 to Lehman, et al., teaches the in situ regeneration of spent catalyst for use in an ebullated bed. The spent catalyst is “per se” regenerated, rather than being used as a binder.
SU 882918 is to the same end, with a fluidized catalyst useful in FCC processes, but not non-FCC processes.
SU 1728157 teaches the binding of waste catalyst with Al(OH)3, rather than using the spent catalyst as a binder.
CA 2487726 also deals with an FCC process where fluidized particles are produced. Kaolin is used as an additive.
Costa, et al., IJRET:114-122 (September 2014), teaches adding spent, FCC catalysts to sand, to produce mortar. This teaching is similar to that of Antonovic, et al., J. Therm. Analysis & Coloremetry, 109(2):537-544 (February 2012).
Fundamentally, the art deals with FCC processes which differ considerably from hydrocracking, as described infra. The later are the subject of the invention, which will be seen from the disclosure which follows.